Currently each time a screen resolution or setting change occurs, fbdev_destroy, fbdev_init and fbdev_set_mode are called in sequence, trying to destroy context and surface (though context pointer seems to remain unchanged) and create again both of them.
However it seems something is wrong with egl_destroy, as after the call fps drops from 60 to 33fps in GUI with huge performance impact, at least with libmali.
Philosophy is changed with this commit to avoid destroying and creating context and surface each time (creation only occurs in fbdev_init and egl_destroy is called only if retroarch is shutting down).
As a minor modification, framebuffer is resetted to 0 on retroarch shutdown to avoid any chance of freezed screen effect.
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